- ID:
- ivo://CDS.VizieR/J/PASP/109/977
- Title:
- VI photometry of CG Muscae
- Short Name:
- J/PASP/109/977
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained extensive photometry of the suspected cataclysmic variable CG Muscae, and find that it is in fact an RR Lyrae star. We measure its light curve parameters and derive physical parameters including metal abundance, reddening, and distance. We also have discovered three new variables in the nearby field. We suspect that two are contact binary stars, while the third is too faint to determine its variability type with certainty. (c)Astronomical Society of the Pacific
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- ID:
- ivo://CDS.VizieR/J/AJ/124/3222
- Title:
- VI photometry of Draco and UMi galaxies
- Short Name:
- J/AJ/124/3222
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present (V, I) photometry of two wide (~25x25arcmin^2^) fields centered on the low surface brightness dwarf spheroidal galaxies Draco and Ursa Minor. New estimates of the distance to these galaxies are provided [(m-M)_0_(UMi)=19.41+/-0.12 and (m-M)_0_(Dra)=19.84+/-0.14], and a comparative study of their evolved stellar population is presented.
- ID:
- ivo://CDS.VizieR/J/A+A/411/361
- Title:
- VI photometry of extra-galactic Cepheids
- Short Name:
- J/A+A/411/361
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we recalibrate the Cepheid distance to some nearby galaxies observed by the HST Key Project and the Sandage-Tammann-Saha group. We use much of the Key Project methodology in our analysis but apply new techniques, based on Fourier methods to estimate the mean of a sparsely sampled Cepheid light curve, to published extra-galactic Cepheid data. We also apply different calibrating PL relations to estimate Cepheid distances, and investigate the sensitivity of the distance moduli to the adopted calibrating PL relation. We re-determine the OGLE LMC PL relations using a more conservative approach and also study the effect of using Galactic PL relations on the distance scale.
- ID:
- ivo://CDS.VizieR/J/AJ/116/469
- Title:
- VI photometry of galactic cepheids
- Short Name:
- J/AJ/116/469
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a survey of a 6deg^2^ region near l=60{deg}, b=0{deg} to search for distant Milky Way Cepheids. Few such Cepheids are known at distances >~ R_0_, limiting large-scale Milky Way disk models derived from Cepheid kinematics; this work was designed to find a sample of distant Cepheids for use in such models. The survey was conducted in the V and I bands over eight epochs, to a limiting I~=18, with a total of almost 5 million photometric observations of over 1 million stars. We present a catalog of 578 high-amplitude variables discovered in this field. Cepheid candidates were selected from this catalog on the basis of variability and color change and observed again the following season. We confirm 10 of these candidates as Cepheids with periods from 4 to 8 days, most at distances greater than 3kpc. Many of the Cepheids are heavily reddened by intervening dust, some with implied extinction A_V_>10mag. With a future addition of infrared photometry and radial velocities, these stars alone can provide a constraint on R_0_ to 8% and in conjunction with other known Cepheids should provide good estimates of the global disk potential ellipticity.
- ID:
- ivo://CDS.VizieR/J/AcA/60/295
- Title:
- VI photometry of Galactic disk field stars
- Short Name:
- J/AcA/60/295
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present OGLE-III Photometric Maps of the Galactic disk fields observed during the OGLE-III campaigns for low luminosity transiting objects that led to the discovery of the first transiting exoplanets. The maps contain precise, calibrated VI photometry of about 9 million stars from 21 OGLE-III fields in the Galactic disk observed in the years 2002-2009 and covering more than 7 square degrees in the sky. Precise astrometry of these objects is also provided. We discuss quality of the data and present a few color-magnitude diagrams of the observed fields.
- ID:
- ivo://CDS.VizieR/J/AcA/53/27
- Title:
- VI photometry of MM1 and MM7 OGLE fields
- Short Name:
- J/AcA/53/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As a result of the reanalysis of the OGLE-I observations by means of the image subtraction method, we present the first part of a catalog, consisting of data for variable stars in four Galactic fields observed by OGLE-I, viz. MM1-A, MM1-B, MM7-A, and MM7-B. In total, 2016 variable stars have been found. This increased the number of known variable stars in these fields more than twofold. We comment on the detectability of the variable stars in previous studies.
- ID:
- ivo://CDS.VizieR/J/ApJ/523/540
- Title:
- VI photometry of new Cepheids in NGC 3319
- Short Name:
- J/ApJ/523/540
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The distance to NGC 3319 has been determined from Cepheid variable stars as part of the Hubble Space Telescope Key Project on the Extragalactic Distance Scale. Thirteen and four epochs of observations, using filters F555W (V) and F814W (I), respectively, were made with the Wide Field Planetary Camera 2. Thirty-three Cepheid variables between periods of 8 and 47 days were discovered. Adopting a Large Magellanic Cloud distance modulus of 18.50{+/-}0.10 mag and extinction of E(V-I)=0.13 mag, a true reddening-corrected distance modulus (based on an analysis employing the ALLFRAME software package) of 30.78 {+/-}0.14 (random) {+/-}0.10 (systematic) mag and the extinction of E(V-I)=0.06 mag were determined for NGC 3319. This galaxy is the last galaxy observed for the HST H_o_ Key Project.
- ID:
- ivo://CDS.VizieR/J/ApJ/514/614
- Title:
- VI photometry of new Cepheids in NGC 3198
- Short Name:
- J/ApJ/514/614
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the detection of Cepheid variable stars and a new distance to the Sc spiral NGC 3198. NGC 3198 is one of 25 galaxies that have been observed with the WFPC2 of the Hubble Space Telescope (HST) for the purpose of measuring Cepheid distances. Eighteen of these galaxies were targeted by the HST Key Project on the Extragalactic Distance Scale, whose objective is to calibrate a variety of secondary distant indicators and determine the Hubble constant to an accuracy of 10%. NGC 3198 was selected as part of this sample because its type and orientation make it very suitable as a Tully-Fisher calibrator. The WFPC2 data are comprised of 13 epochs in F555W ({~}V) and five epochs in F814W ({~}I). Two different crowded-field photometry packages (DAOPHOT/ALLFRAME and DoPHOT) were used. The magnitudes derived from these two packages agree to within a few percent. We identified 78 Cepheid candidates in the period range from eight to >50 days, of which 52 were selected for establishing the distance modulus. Period-luminosity relations were constructed in Johnson V and Kron-Cousins I by transforming the F555W and F814W to the standard system. We adopted a distance modulus of {mu}_o_=18.50{+/-}0.10 mag and mean reddening of E(B-V)=0.10 mag to the Large Magellanic Cloud Cepheids and found a true distance modulus to NGC 3198 of {mu}_o_=30.80{+/-}0.16 (random) {+/-}0.12 (systematic) mag. This modulus corresponds to a distance of 14.5 Mpc, with random and systematic errors of {+/-}1.2 and {+/-}0.9 Mpc, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJ/507/655
- Title:
- VI photometry of new Cepheids in NGC 2541
- Short Name:
- J/ApJ/507/655
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the detection of Cepheids and a new distance to the spiral galaxy NGC 2541, based on data obtained with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope (HST). A total of 25 exposures (divided into 13 epochs) were obtained using the F555W filter (transformed to Johnson V), and nine exposures were obtained (divided into five epochs) using the F814W filter (transformed to Cousins I). Photometric reduction of the data is performed using two independent packages, DoPHOT and DAOPHOT II/ALLFRAME, which give very good agreement in the measured magnitudes. A total of 34 bona fide Cepheids, with periods ranging from 12 to over 60 days, are identified based on both sets of photometry. By fitting V and I period-luminosity relations, apparent distance moduli are derived assuming a Large Magellanic Cloud distance modulus and mean color excess of {mu}_LMC_=18.50+/-0.10mag and E(B-V)=0.10mag, respectively. Adopting A(V)/E(V-I)=2.45, we obtain a true distance modulus to NGC 2541 of {mu}_0_=30.47+/-0.11 (random) +/-0.12 (systematic) mag (D=12.4+/-0.6 [random] +/-0.7 [systematic] Mpc), and a total (Galactic plus internal) mean color excess E(B-V)=0.08+/-0.05 (internal error) mag.
- ID:
- ivo://CDS.VizieR/J/ApJ/512/48
- Title:
- VI photometry of new Cepheids in NGC 4725
- Short Name:
- J/ApJ/512/48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The distance to NGC 4725 has been derived from Cepheid variables as part of the Hubble Space Telescope Key Project on the Extragalactic Distance Scale. Thirteen F555W (V) and four F814W (I) epochs of cosmic-ray-split Wide Field and Planetary Camera 2 observations were obtained. Twenty Cepheids were discovered, with periods ranging from 12 to 49 days. Adopting a Large Magellanic Cloud distance modulus and extinction of 18.50{+/-}0.10 mag and E(V-I)=0.13 mag, respectively, a true reddening-corrected distance modulus (based on an analysis employing the ALLFRAME software package) of 30.50{+/-}0.16 (random) {+/-}0.17 (systematic) mag was determined for NGC 4725. The corresponding of distance of 12.6{+/-}1.0 (random) {+/-}1.0 (systematic) Mpc is in excellent agreement with that found with an independent analysis based upon the DoPHOT photometry package. With a foreground reddening of only E(V-I)=0.02, the inferred intrinsic reddening of this field in NGC 4725, E(V-I)=0.19, makes it one of the most highly reddened fields encountered by the HST Key Project to date.
